irregular z axis

[Alec Joubert <alec@xxxxxxxxxxxxxxxxxx>]

Dear Ferret users

The example from a previous listing below lists a solution to the problem
of of an irregularly-spaced depth or height axis, supplied by Steve
Hankin.

I have followed the suggestion, by creating my own height variable within
ferret, and then trying to define a grid using "from_data".

I get the following error-message:
 **ERROR: improper grid or axis definition: data for DEFINE
AXIS/FROM_VARIABLE is not monotonic

Does anyone know what this refers to, and how I might go about sorting it
out?

thanks

Alec

-------------------------------------------------------------------------------
Dr Alec Joubert                   
Climatology Research Group         Tel:   +27 11 716 2998
University of the Witwatersrand    Fax    +27 11 716 3161
P.O. Wits 2050                     Email: alec@crg.bpb.wits.ac.za    
SOUTH AFRICA                       WWW:   http://crg.bpb.wits.ac.za
-------------------------------------------------------------------------------

---------- Forwarded message ----------
Date: Wed, 12 Nov 1997 14:33:29 -0800
From: Steve Hankin <hankin@rogue.pmel.noaa.gov>
To: Kim Seong-Joong <ksj@manatee.TAMU.EDU>, ferret_users@ferret.wrc.noaa.gov
Subject: re: LDEO depths

	Ferret how-to:	*** USING AXIS COORDINATES ON_THE_FLY ***

=============

On Nov 12,  4:02pm, Kim Seong-Joong wrote:
> Subject:
> Hello folks,
>
>         Please help me. I am trying to calculate density using annual mean
>  temperature and salinity from LDEO under ferret. Problem is the depth
increment
>  is not constant. There are 33 levels with different increments from 0.0 m to
> 5500 m. Does anybody know how to convert the levels into real depths using
any
>  ferret commands. Thank you.
>-- End of excerpt from Kim Seong-Joong

==========

Hi Kim,

If you have the depths available in a Ferret variable (i.e if you could type
	yes? LIST my_depths
and see your depths) then you can use this technique:

  DEFINE AXIS/DEPTH/FROM_DATA/NAME=LDEOdepths/Z/units=meters my_depths
  LET my_temp = temp[gz=my_depths@asn]


Now use my_temp instead of temp -- my_temp will be based on the Z axis of
irregular depths.

	- steve



-- 

		|  NOAA/PMEL               |  ph. (206) 526-6080  
Steve Hankin	|  7600 Sand Point Way NE  |  FAX (206) 526-6744
		|  Seattle, WA 98115-0070  |  hankin@pmel.noaa.gov